本研究以民國86年至民國93年上市公司財務報表資料探討我國企業赴中國大陸投資相關因素對有效稅率的影響。經本研究實證結果發現，有赴中國大陸投資的上市公司其有效稅率低於未赴中國大陸投資者；上市公司透過間接方式投資大陸地區之比重愈高者以及大陸地區投資獲利愈高者，由於有較多租稅規劃的空間，其有效稅率愈低。整體而言，在研究期間中，我國上市公司之平均有效稅率明顯低於營利事業所得稅名目最高邊際稅率；公司規模對有效稅率有負向影響，符合政治權力假說；本研究以長期負債、固定資產、存貨、研究發展費用做為投資理財決策的代理變數，皆與有效稅率呈現負相關，因此投資理財決策具有稅盾效果，可以降低公司稅負；另外，上市公司的獲利能力愈佳，有效稅率也愈高；證券以及土地交易所得等免稅所得較多的上市公司，有效稅率較低。上述分析顯示，上市公司赴中國大陸投資因素對於其租稅負擔有顯著影響，值得政府有關單位做為研擬相關法規的參考。 / This study uses 1997-2004 financial statement data to explore the relationships between investment in Mainland China and the effective tax rates (ETRs) of listed companies in Taiwan. The empirical results show that investment in Mainland China of the listed companies has a negative and significant impact on the ETRs. This study finds that ETRs is negatively related with the scale of indirect investment and the level of profit of subsidiaries in Mainland China, perhaps due to a higher flexibility and feasibility of tax planning. Our results also reveal that average ETRs of listed companies are substantially lower than the statutory tax rate of the Income Tax Act of R.O.C. Small firms are more likely to have greater ETRs, supporting the political power hypothesis. Moreover, because of the tax shield effects, long-term debts, fixed assets, inventories, and R&D expenses, all as proxies for the financial decisions, have negative and significant impacts on the ETRs of listed companies. Finally, ceteris paribus, profitable companies tend to have higher ETRs, and tax-exempt capital gains from stock and land transactions also reduce the ETRs of listed companies. These findings indicate that investment in Mainland China by listed companies plays an important role in their tax burdens, and this fact should be taken into account by the government in devising future tax reforms.